bbPress.org

There isn’t currently a way to do what you are asking, there probably is a way to disable stickies site wide for everyone (including admin/keymaster) but that is not what you are looking for.

With the default permissions a moderator has I think there are far more dangerous options available to them such as deleting other users topics and replies.

In this regard you are offering any moderators of your forum a certain degree of trust. I would suggest you extend this trust to your moderators in regards to stickies. You can make this part of your ‘moderator’ rules/policy and ask all your moderators abide by this policy.